Composite fiber and method for forming the same

ABSTRACT

A composite fiber is provided. The composite fiber includes a first region and a second region. The component of the first region includes a coloring agent and a resin. The component of the second region includes a crosslinked thermoplastic polymer and the crosslinked thermoplastic polymer includes gel particles with an average particle size no more than 1000 nm. A method for forming the composite fiber is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/343,210, filed on May 31, 2016, which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a composite fiber and a method for forming the same.

BACKGROUND

In the textile fiber industry, there are numerous polyamide (nylon), polyester, and polyolefin products. However, because these materials are hydrophobic, their fiber products have shortcomings such as being non-hygroscopic and non water-absorbing. In order to improve the aforementioned shortcomings, in the past, hydrophobic polymers such as polyester and polymers with hydrophilicity such as ethylene vinyl alcohol copolymer (EVOH) have been used to form a core-sheath type composite fiber by composite spinning to improve the hydrophilic property of polyester fibers.

However, after performing a composite spinning on materials with different hydrophilicity and hydrophobicity, the adherence of the interface between the two materials becomes weaker and therefore a separation often occurs, which results in filaments breaking during post-processing. This affects the operation or causes a fluff forming on the finished fabrics, which is detrimental to its appearance. In addition, during the stage of textile dyeing of the composite fiber formed of polyester and ethylene vinyl alcohol copolymer, because the melting points and softening points of ethylene vinyl alcohol copolymer (EVOH) on the fiber surface are low, swelling, melting and sticking often occur between fibers, which results in the poor handling of the finished fabrics.

Therefore, an improved composite fiber material and a process thereof are currently needed to solve the aforementioned problems.

SUMMARY

According to an embodiment, the present disclosure provides a composite fiber, including: a first region, wherein the components of the first region include a resin; and a second region, wherein the components of the second region include a crosslinked thermoplastic polymer; wherein the crosslinked thermoplastic polymer includes gel particles with an average particle size no larger than 1000 nm. Alternatively, according to another embodiment, the components of the first region further include a coloring agent.

According to another embodiment, the present disclosure provides a method for forming a composite fiber, including: blending 96˜99.79 wt % of thermoplastic polymer, 0.1˜1.5 wt % of crosslinking agent, 0.1˜1.5 wt % of dispersant to form a mixture; adding 0.01˜1 wt % of crosslinking initiator to the mixture and performing kneading to form a crosslinked thermoplastic polymer; stranding and granulating the crosslinked thermoplastic polymer to form a crosslinked modified particle; and performing a composite melt-spinning to the crosslinked modified particle and a resin, wherein the resin may or may not include a coloring agent.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1A illustrates a cross-sectional schematic diagram of a composite fiber according to an embodiment of the present disclosure.

FIG. 1B illustrates a cross-sectional schematic diagram of a composite fiber according to an embodiment of the present disclosure.

FIG. 1C illustrates a cross-sectional schematic diagram of a composite fiber according to an embodiment of the present disclosure.

FIG. 1D illustrates a cross-sectional schematic diagram of a composite fiber according to an embodiment of the present disclosure.

FIG. 1E illustrates a cross-sectional schematic diagram of a composite fiber according to an embodiment of the present disclosure.

FIG. 2 illustrates a flow chart of the method for forming a composite fiber according to an embodiment of the present disclosure.

FIG. 3A and FIG. 3B illustrate cross-sectional Scanning Electron Microscope images of composite fibers according to an embodiment of the present disclosure.

FIG. 4A and FIG. 4B illustrate cross-sectional Scanning Electron Microscope images of composite fibers according to an embodiment of the present disclosure.

FIG. 5 illustrates a cross-sectional Scanning Electron Microscope image of a composite fiber according to an embodiment of the present disclosure.

FIG. 6 illustrates a cross-sectional Scanning Electron Microscope image of a composite fiber according to an embodiment of the present disclosure.

FIG. 7 illustrates a cross-sectional Scanning Electron Microscope image of a composite fiber according to an embodiment of the present disclosure.

FIG. 8 illustrates a cross-sectional Scanning Electron Microscope image of a composite fiber according to an embodiment of the present disclosure.

FIG. 9 illustrates a cross-sectional Scanning Electron Microscope image of a composite fiber according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

The following provides many different embodiments according to different features of the present disclosure. In the present disclosure, specific components and arrangements are described for simplicity. However, the present disclosure is not limited to these embodiments. For example, the formation of a first component on a second component in the description may include embodiments in which the first and second components are formed in direct contact, and may also include embodiments in which additional components may be formed between the first and second components, such that the first and second components may not be in direct contact. In addition, for the purpose of simplicity and clarity, the present disclosure may repeat reference numerals and/or letters in the various examples. However, it does not in itself dictate a specific relationship between the various embodiments and/or configurations discussed.

Embodiments of the present disclosure provide a composite fiber. By modifying the hydrophilic thermoplastic polymer through crosslinking, the separation of the hydrophilic materials from the hydrophobic materials at the interface between them is minimized, thereby reducing the problem of filament-breaking in post-processing, or of fluff forming on the finished fabrics, which is detrimental to the appearance. By using the method for forming the composite fiber provided by embodiments of the present disclosure, the problems of poor handling of the finished fabrics resulting from the swelling of a thermoplastic polymer such as ethylene vinyl alcohol copolymer (EVOH) on the fiber surface, and melting and sticking between fibers may also be solved.

Trifunctional crosslinking agents are used in the embodiments of the present disclosure to perform a crosslinking modification to the thermoplastic polymer with hydrophilicity. Then, a composite spinning is performed on the crosslinked hydrophilic thermoplastic polymer and hydrophobic resins. By the crosslinking modification of the hydrophilic thermoplastic polymer, separation at the interface between the two materials can be improved. In addition, the hydrophobic resin used in the embodiments of the present disclosure may first be blended with coloring agents, and then composite spun with the modified hydrophilin thermoplastic polymer to form a colored composite fiber. The coloring agents used in the embodiments of the present disclosure may also be blended with resins during the step of composite spinning.

In an embodiment of the present disclosure, a composite fiber is provided. The composite fiber includes a first region A and a second region B.

In an embodiment of the present disclosure, the components of the first region A include a resin. In another embodiment of the present disclosure, the components of the region A further include a coloring agent, and the weight percentage of the aforementioned coloring agent in the components of the first region A is ≦12 wt %. The aforementioned coloring agent may include organic dyes, inorganic pigments, organic pigments, special pigments such as metal fragments, fluorescent pigments, and nacreous pigments, etc, or a combination thereof. In one embodiment, the weight percentage of the aforementioned coloring agent in the components of the first region A is ≦8 wt %. The aforementioned resin may be a hydrophobic resin, for example, including polyester resin, polyamide resin, polyolefin resin, or a copolymer of the aforementioned resins. In one embodiment, the aforementioned resin may include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or a combination thereof.

In an embodiment of the present disclosure, the components of the second region B include a crosslinked thermoplastic polymer. The aforementioned thermoplastic polymer may be a hydrophilic thermoplastic polymer such as ethylene vinyl alcohol copolymer (EVOH). In some embodiments, the ethylene mole percentage of ethylene vinyl alcohol copolymer (EVOH) may be 25˜50%. In some embodiments, the ethylene mole percentage of ethylene vinyl alcohol copolymer (EVOH) may be 35˜45%. It should be noted that, after the crosslinking reaction, if the average particle size of the insoluble gel particles produced is too large, the molding processing of fibers would be impeded. However, in the embodiments of the present disclosure, the average particle size of the insoluble gel particles produced in the components of the second region B may be ≦1000 nm, which reaches the standard to be spun of the current commercial fibers. That is, the crosslinked thermoplastic polymer in the second region B includes gel particles with an average particle size no larger than 1000 nm. In some embodiments, the average particle size of the gel particles produced in the components of the second region B may be ≦500 nm. In one embodiment, the average particle size of the gel particles produced in the components of the second region B may be ≦350 nm. In one embodiment, the average particle size of the gel particles produced in the components of the second region B may be ≦200 nm.

In one embodiment, the components of the second region B are formed of 96˜99.79 wt % of thermoplastic polymer, 0.1˜1.5 wt % of crosslinking agent, 0.1˜1.5 wt % of dispersant, and 0.01˜1 wt % of crosslinking initiator.

In one embodiment, the weight percentage of thermoplastic polymer in the components of the second region B may be about 96.0, 96.5, 97.0, 97.5, 98.0, 98.5, 99.0, 99.5, or 99.79 wt %. The thermoplastic polymer may be a hydrophilic thermoplastic polymer such as ethylene vinyl alcohol copolymer (EVOH). In some embodiments, the ethylene mole percentage of ethylene vinyl alcohol copolymer (EVOH) may be, for example, 25˜50% or 35˜45%.

In some embodiments, the weight percentage of crosslinking agent in the components of the second region B may be about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5 wt %. In some embodiments, the crosslinking agent may include triallyl ester compounds, triallyl amine compounds, or a combination thereof. For example, triallyl ester compounds may include triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), triallyl cyanurate (TAM), or a combination thereof. For example, triallyl amine compounds may include triallyl amine, triallyl-ammoniumcyanurate, or a combination thereof.

In some embodiments, the weight percentage of dispersant in the components of the second region B may be about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, or 1.5 wt %. In some embodiments, the dispersant may include C₁₅₋₃₈ alkyl, C₁₅₋₃₈ ester, or a mixture thereof. Addition of dispersant is beneficial to the homogeneous dispersion of various constituents in the components of the second region B. In detail, addition of dispersant may prevent the aggregation of the crosslinking agent itself and further promote a homogeneous crosslinking reaction.

In some embodiments, the weight percentage of crosslinking initiator in the components of the second region B may be about 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 1 wt %. In some embodiments, the crosslinking initiator may include benzoyl peroxide, dicumyl peroxide, azobisisobutyronitrile, or a combination thereof. What kind of the crosslinking agent is used depends on the kind of the crosslinking agent used. Addition of the crosslinking agent is beneficial to the performance of the crosslinking reaction.

After the crosslinking reaction, the shear force (melt viscosity (η)×shear rate) of the components of the second region B may be 120˜20 Pa·s×4000˜12000 s⁻¹ at 190˜220° C.

One of the reasons that the separation at the interface of the two materials can be prevented by the crosslinking modification of the hydrophilic thermoplastic polymer is that a van der Waals force is produced between the two materials by the functional groups in the first region A and the second region B. It should be noted that the van der Waals force produced between the functional groups increases the interfacial adherence between the first region A and the second region B, thereby making a better connection between the first region A and the second region B and minimizing the separation at the original interface and making the interface inconspicuous. For example, when the resin used in the first region A and the crosslinking agent used in the second region B both have a benzene ring structure, the van der Waals force between the two regions increases, contributing to the connection between the first region A and the second region B.

The composite fiber provided by the embodiments of the present disclosure may include, but are not limited to, partial oriented yarn (POY), fully oriented yarn (FOY), spin drawn yarn (SDY), draw texturing yarn (DTY), or air textured yarn (ATY).

In the cross section of the composite fiber, the ratio of the area of the first region A and the second region B may be 10:90˜90:10. In some embodiments, the ratio of the area of the first region A and the second region B may be 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, or 90:10. In one embodiment, in the cross section of the composite fiber, at least a portion of the second region is located at the outer peripheral portion of the cross section. In the cross section of the composite fiber, as long as the second region B is located at the peripheral portion of the cross section, the problems of poor abrasion fastness, washing fastness, and non-permanent type moisture absorption and sweat release of the traditional chemical fiber can be solved through the protective function of the crosslinked thermoplastic polymer in the second region B. In one embodiment, in the cross section of the composite fiber, the first region A is a core portion and the second region B is a shell portion.

FIG. 1A to FIG. 1E illustrate the cross-sectional schematic diagrams of the composite fiber provided by the present disclosure. According to the different arrangements of the first region A and the second region B on the cross section of the composite fiber, the types of composite fiber may include core-shell type, segment-pie type, or sea-islands type. For example, in some embodiments, the composite fiber may be a concentric shell-core type fiber as shown in FIG. 1A, or an eccentric shell-core type fiber as shown in FIG. 1B. In some other embodiments, the composite fiber may be a segment-pie type fiber as shown in FIGS. 1C, 1D. In some other embodiments, the composite fiber may be a sea-islands type fiber as shown in FIG. 1E. It should be noted that FIG. 1A to FIG. 1E are shown only for the purpose of demonstration and are not intended to be used to limit the present disclosure. As long as the second region B, which includes the crosslinked thermoplastic polymer component, of the composite fiber is disposed at the whole surface of the composite fiber, it may be used in the present disclosure. For example, the number of segmentations of the segment-pie type fiber shown in FIGS. 1C, 1D and the number of islands of the sea-islands type fiber shown in FIG. 1E may be adjusted to suit practical needs by those skilled in the art. Also, those skilled in the art may arbitrarily design the shape and diameter of the cross section of the resulting composite fiber by the shape and size of the nozzle hole.

In another embodiment of the present disclosure, a method for forming a composite fiber is provided. FIG. 2 illustrates a flow chart of the method 200 for forming the composite fiber according to an embodiment of the present disclosure. First, the method 200 begins with step 202 by blending 96˜99.79 wt % of thermoplastic polymer, 0.1˜1.5 wt % of crosslinking agent, and 0.1˜1.5 wt % of dispersant to form a mixture. Next step 204 is performed by adding 0.01˜1 wt % of crosslinking initiator to the mixture and kneading it to form a crosslinked thermoplastic polymer. For the purpose of simplicity and clarity, the relevant paragraphs above may be referred to for a description of the kinds and functions of the thermoplastic polymer, crosslinking agent, dispersant, and crosslinking initiator added in the method 200, and to avoid unnecessary repetition this description is not repeated herein.

In step 204, the kneading may be performed by using, for example, a twin-screw kneading machine or another appropriate kneading machine. The rotating speed of the screw may be, for example, 200˜300 rpm. The kneading time may be about 1˜10 minutes, and the kneading temperature may be about 170˜230° C. In one embodiment, the kneading time may be about 10 minutes, and the kneading temperature may be about 200˜230° C. However, the various processing parameters for the kneading may be adjusted to suit practical needs, and are not limited to the parameters provided.

It should be noted that, during the kneading process, the thermoplastic polymer is in a molten state. At this time, the crosslinking agent uses its functional group of —C═C double bond to perform a crosslinking reaction with the molten-state thermoplastic polymer, thereby making the thermoplastic polymer become a crosslinked thermoplastic polymer. By controlling the adding ratio of the thermoplastic polymer and the crosslinking agent, the ratio of the crosslinked thermoplastic polymer in the whole crosslinked thermoplastic polymer enables the crosslinked thermoplastic polymer to have flow characteristics. When the ratio of the crosslinking agent is too high, most of the thermoplastic polymer forms a network structure which makes the thermoplastic polymer lose fluidity and the thermoplastic polymer cannot be spun to form fibers. When the ratio of the crosslinking agent is too low, the ratio of performing crosslinking reaction of the thermoplastic polymer is too low, such that the purpose of modifying the thermoplastic polymer cannot be reached.

In step 204, the a shear force (melt viscosity (η)×shear rate) of the crosslinked thermoplastic polymer including the aforementioned crosslinked thermoplastic polymer may be 120˜20 Pa·s×4000˜12000 s⁻¹ at 190˜220° C. Also, the average particle size of the insoluble gel particles in the crosslinked thermoplastic polymer is controlled to be ≦1000 nm, which may not impede the following molding process of fibers.

Next, the method 200 proceeds to step 206 by stranding and granulating the crosslinked thermoplastic polymer to form a crosslinked modified particle. The steps of stranding and granulating may be performed according to the methods and conditions known in the art.

Finally, the method 200 proceeds to step 208 by performing a composite melt-spinning to the crosslinked modified particle and a coloring agent-containing resin (does not contain a coloring agent in another embodiment). The aforementioned coloring agent-containing resin may be a master batch formed by a well-known production process. The weight percentage of the coloring agent of the coloring agent-containing resin is ≦12 wt %, or ≦8 wt % in the coloring agent-containing resin. The kinds of the coloring agent may refer to the related paragraphs described above.

For the composite fiber provided by the embodiments of the present disclosure, there is no need to perform an acetalation of hydroxyl groups of ethylene vinyl alcohol copolymer (EVOH) on the fiber surface by using dialdehyde compounds in post-processing. On the contrary, in the embodiments of the present disclosure, the crosslinked modified thermoplastic polymer is formed first, and then composite is melt-spun with the resin to form a composite fiber. By the crosslinked modified thermoplastic polymer, the separation at the interface between the two materials of the known composite fiber is minimized. The composite fiber provided by the embodiments of the present disclosure can be color-deepened, and the finished fabrics thereof have not only good handling and appearance, but they also exhibit good moisture absorption and sweat release.

The various Embodiments and Comparative Examples are listed below to illustrate the composite fibers provided by the present disclosure and the characteristics thereof.

Preparation Examples 1˜4: Crosslinked Modified Particles (Triallyl Ester Compounds were Used as Crosslinking Agents)

First, a crosslinking agent of triallyl isocyanurate (TAIC), ethylene vinyl alcohol copolymer (EVOH) (ethylene mole percentage is 44%), and a dispersant were blended to obtain a mixture. Next, a crosslinking initiator of benzoyl peroxide was added to the above mixture and kneading was performed. The kneading time was about 10 minutes, and the kneading temperature was about 200˜230° C. Then, the product of kneading was stranded and granulated to obtain the crosslinked modified EVOH particle of Preparation Example 1.

The preparation methods of Preparation Examples 2˜4 were the same as Preparation Example 1 except that the constitute ratio of triallyl isocyanurate (TAIC) and ethylene vinyl alcohol copolymer (EVOH) was adjusted to the ratio shown in Table 1. In Preparation Examples 1˜4, the adding ratio of the dispersant was all 0.5 wt %. In Preparation Examples 1˜4, the adding ratio of the crosslinking initiator benzoyl peroxide was all 0.05 wt %, based on the total weight of the crosslinking agent, ethylene vinyl alcohol copolymer (EVOH), and dispersant.

Polymers produce gels after the crosslinking reaction. The gels are insoluble in the solvent. The particle size of gels in the products obtained from the kneading of Preparation Examples 1˜4 was measured by a laser diameter measuring instrument. The results of the measurement are shown in Table 1.

TABLE 1 Thermoplastic Crosslinking polymer Average agent ethylene vinyl particle triallyl alcohol size of gel isocyanurate (TAIC) copolymer (EVOH) particles (nm) Preparation 0.2 99.3 50 Example 1 Preparation 0.5 99.0 158 Example 2 Preparation 0.8 98.7 380 Example 3 Preparation 1.0 98.5 460 Example 4

Preparation Example 5: Crosslinked Modified Particles (Triallyl Amine Compounds were Used as Crosslinking Agents)

The preparation method of Preparation Example 5 was the same as Preparation Example 1 except that triallyl isocyanurate (TAIC) was replaced by triallyl amine. The particle size of gel particles in the product obtained from the kneading of Preparation Example 5 was measured by a laser diameter measuring instrument. The measured average particle size was 45 nm.

Comparative Example 1: Composite Fiber—Un-Crosslinked Modified EVOH (P-EVOH)/PET

Un-crosslinked modified EVOH particles (hereinafter called P-EVOH in abbreviation) with an ethylene mole percentage of 44% were used as the material of a shell component of the composite fiber, and polyethylene terephthalate (PET) particles (intrinsic viscosity (IV): 0.64) were used as the material of the core component of the composite fiber. Composite spinning was performed on the two materials described above. First, after winding at 2800 m/min, extending at 80° C., setting at 150° C., a fully oriented yarn (FOY) was formed. As such, the manufacture of the composite fiber was completed. The specification of the resulting composite fiber includes a spin denier of 80D/36F, a strength of 2.8 (g/d), and an elongation of 25±5(%).

Example 1: Composite Fiber—Crosslinked Modified EVOH (M-EVOH)/PET

Crosslinked modified EVOH particles (hereinafter called M-EVOH in abbreviation) with an ethylene mole percentage of 44% of the Preparation Example 2 were used as the material of a shell component of the composite fiber, and polyethylene terephthalate (PET) particles (IV: 0.64) were used as the material of the core component of the composite fiber. Composite spinning was performed on the two materials described above. First, after winding at 2800 m/min, extending at 80° C., setting at 150° C., a fully oriented yarn (FOY) was formed. As such, the manufacture of the composite fiber was completed. The specification of the resulting composite fiber includes a spin denier of 80D/36F, a strength of 3.2 (g/d), and an elongation of 25±5(%).

FIGS. 3A˜3B illustrate the cross-sectional Scanning Electron Microscope images of the composite fiber formed in Comparative Example 1 under different magnifications. The separation at the interface of the shell and the core of the P-EVOH/PET in Comparative Example 1 is obvious. In comparison, FIGS. 4A˜4B illustrate the cross-sectional Scanning Electron Microscope images of the composite fiber formed in Example 1 under different magnifications. It can be observed that the interface between the shell and the core of M-EVOH/PET of Example 1 becomes indistinct. Compared to Comparative Example 1, the separation of the shell from the core at the interface is significantly reduced.

Example 2: Composite Fiber—M-EVOH/PA

M-EVOH with an ethylene mole percentage of 44% of the Preparation Example 5 (triallyl amine compounds were used as crosslinking agents) were used as the material of a shell component of the composite fiber, and polyamide resin (Formosa Chemical; Sunylon 2NBR Nylon 6) particles (RV value: 2.4) were used as the material of the core component of the composite fiber. Composite spinning was performed on the two materials described above. First, after winding at 3800 m/min, extending at 50° C., setting at 150° C., a fully oriented yarn (FOY) was formed. As such, the manufacture of the composite fiber was completed. The specification of the resulting composite fiber includes a spin denier of 80D/36F, a strength of 3.5 (g/d), and an elongation of 25±5(%).

Example 3: Composite Fiber—M-EVOH/Coloring Agent-Containing PBT

M-EVOH with an ethylene mole percentage of 44% of the Preparation Example 2 were used as the material of a shell component of the composite fiber, and polybutylene terephthalate (PBT) particles (IV value: 0.9) with 0.025 wt % of light purple coloring agent (Tah Kong Chemical; PV 23) were used as the material of the core component of the composite fiber. Composite spinning was performed on the two materials described above. First, after winding at 2800 m/min, extending at 70° C., setting at 150° C., a fully oriented yarn (FOY) was formed. As such, the manufacture of the composite fiber was completed.

Examples 4˜6: Composite Fiber—M-EVOH/Coloring Agent-Containing PBT

The preparation methods of Examples 4˜6 are the same as Example 3 except that the light purple coloring agent was replaced by light green coloring agent (Tah Kong Chemical; PG-7) in Example 4, the light purple coloring agent was replaced by orange coloring agent (Tah Kong Chemical; PO-16) in Example 5, and the light purple coloring agent was replaced by yellow coloring agent (Tah Kong Chemical; PY3) in Example 6.

The specifications of the partial oriented yarn (POY) composite fibers obtained in the above Examples 3˜6 are shown in Table 2. The specifications of the fully oriented yarn (FOY) composite fibers obtained in the above Examples 3˜6 are shown in Table 3.

TABLE 2 Example 3 Example 4 Example 5 Example 6 Color of the light purple light green orange yellow coloring agent Denier (D) 120D/36F 120D/36F 120D/36F 120D/36F Strength (g/d) 2.17 2.32 1.76 1.66 (CV %) (1.7) (1.6) (2.4) (2.2) Elongation 71.0 77.6 106.4 97.5 (%)(CV %) (1.9) (3.9) (5.9) (4.1)

TABLE 3 Example 3 Example 4 Example 5 Example 6 Color of the light purple light green orange yellow coloring agent Denier (D) 78D/36F 78D/36F 78D/36F 78D/36F Strength (g/d) 3.36 3.52 2.77 2.80 (CV %) (1.5) (2.2) (2.5) (1.6) Elongation 26.7 27.8 32.9 21.7 (%)(CV %) (5.7) (6.6) (9.9) (9.0)

The appearance of the colored composite fibers obtained in Examples 3˜6 was observed and the cross-sectional images were obtained by a Scanning Electron Microscope, as shown in FIGS. 5˜8. It was found that the molding of the colored composite fibers formed in Examples 3˜6 was good, and the interface between the shell and the core of M-EVOH/PBT was not obvious. Compared to Comparative Example 1, the separation of the shell from the core at the interface was significantly reduced.

Example 7: Composite Fiber—M-EVOH/Coloring Agent-Containing PA

M-EVOH with an ethylene mole percentage of 44% of the Preparation Example 5 (triallyl amine compounds were used as crosslinking agents) were used as the material of a shell component of the composite fiber, and polyamide resin (Formosa Chemical: N6) particles (RV value: 2.4) containing 0.025 wt % of blue powder (Tah Kong Chemical; PB-15) were used as the material of the core component of the composite fiber. Composite spinning was performed on the two materials described above. First, after winding at 3800 m/min, extending at 50° C., setting at 150° C., a fully oriented yarn (FOY) was formed. As such, the manufacture of the composite fiber was completed. The specification of the resulting composite fiber includes a spin denier of 80D/36F, a strength of 3.4 (g/d), and an elongation of 25±5(%). The appearance of the colored composite fiber obtained in Example 7 was observed and the cross sectional image was obtained by a Scanning Electron Microscope, as shown in FIG. 9. It can be observed that the molding of the colored composite fiber formed in Example 9 was good, and the interface between the shell and the core of M-EVOH/PA was not obvious. Compared to Comparative Example 1, the separation of the shell from the core at the interface was significantly reduced.

The results of the Examples described above can prove that by performing a crosslinking modification on the thermoplastic polymer, the separation at the interface of the composite fiber formed by performing a composite melt-spinning on the crosslinked modified thermoplastic polymer is significantly reduced. Also, the fibers have good molding and good physical properties such as spinnability and elongation. In addition, the composite fiber formed by the coloring agent-containing resins and crosslinked modified thermoplastic polymer used in the present disclosure can be color-deepened. The finished fabrics not only have good handling and appearance, but they also exhibit good moisture absorption and sweat release.

While the present disclosure has been described by several embodiments above, the present disclosure is not limited to the disclosed embodiments. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protected scope of the present disclosure should be indicated by the following appended claims. 

What is claimed is:
 1. A composite fiber, comprising: a first region, wherein the components of the first region comprise a resin; and a second region, wherein the components of the second region comprise a crosslinked thermoplastic polymer; wherein the crosslinked thermoplastic polymer comprises gel particles with an average particle size no larger than 1000 nm.
 2. The composite fiber as claimed in claim 1, wherein the components of the first region further comprise a coloring agent.
 3. The composite fiber as claimed in claim 2, wherein the weight percentage of the coloring agent in the components of the first region is ≦12 wt %.
 4. The composite fiber as claimed in claim 1, wherein the first region and the second region are connected through a van der Waals force.
 5. The composite fiber as claimed in claim 1, wherein the resin comprises polyester resin, polyamide resin, polyolefin resin, or a copolymer of the aforementioned resins.
 6. The composite fiber as claimed in claim 1, wherein the thermoplastic polymer is ethylene vinyl alcohol copolymer (EVOH), and the mole percentage of ethylene is 25˜50%.
 7. The composite fiber as claimed in claim 1, wherein the components of the second region are formed of 96˜99.79 wt % of the thermoplastic polymer, 0.1˜1.5 wt % of a crosslinking agent, 0.1˜1.5 wt % of a dispersant, and 0.01˜1 wt % of a crosslinking initiator.
 8. The composite fiber as claimed in claim 7, wherein the crosslinking agent is triallyl ester compound, triallyl amine compound, or a combination thereof.
 9. The composite fiber as claimed in claim 8, wherein the triallyl ester compound comprises triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), triallyl trimesate (TAM), or a combination thereof, and the triallyl amine compound comprises triallyl amine, triallyl-ammoniumcyanurate, or a combination thereof.
 10. The composite fiber as claimed in claim 7, wherein the dispersant comprises C₁₅₋₃₈ alkyl, C₁₅₋₃₈ ester, or a mixture thereof.
 11. The composite fiber as claimed in claim 7, wherein the crosslinking initiator comprises benzoyl peroxide, dicumyl peroxide, azobisisobutyronitrile, or a combination thereof.
 12. The composite fiber as claimed in claim 1, wherein the shear force (melt viscosity (η)×shear rate) of the components of the second region is 120˜20 Pa·s×4000˜12000 s⁻¹ at 190˜220° C.
 13. The composite fiber as claimed in claim 1, wherein in a cross section of the composite fiber, the ratio of the areas of the first region and the second region is 10:90˜90:10.
 14. The composite fiber as claimed in claim 1, wherein in a cross section of the composite fiber, at least a portion of the second region is located at the outer peripheral portion of the cross section.
 15. The composite fiber as claimed in claim 13, wherein in a cross section of the composite fiber, the first region is a core portion and the second region is a shell portion.
 16. A method for forming a composite fiber, comprising: blending 96˜99.79 wt % of a thermoplastic polymer, 0.1˜1.5 wt % of a crosslinking agent, 0.1˜1.5 wt % of a dispersant to form a mixture; adding 0.01˜1 wt % of a crosslinking initiator to the mixture and performing kneading to form a crosslinked thermoplastic polymer; stranding and granulating the crosslinked thermoplastic polymer to form a crosslinked modified particle; and performing a composite melt-spinning to the crosslinked modified particle and a resin.
 17. The method for forming the composite fiber as claimed in claim 16, wherein the thermoplastic polymer is ethylene vinyl alcohol copolymer (EVOH), and the mole percentage of ethylene is 25˜50%.
 18. The method for forming the composite fiber as claimed in claim 16, wherein the crosslinking agent comprises triallyl ester compound, triallyl amine compound, or a combination thereof.
 19. The method for forming the composite fiber as claimed in claim 18, wherein the triallyl ester compound comprises triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), triallyl trimesate (TAM), or a combination thereof, and the triallyl amine compound comprises triallyl amine, triallyl-ammoniumcyanurate, or a combination thereof.
 20. The method for forming the composite fiber as claimed in claim 16, wherein the kneading time is 1˜10 minutes, and the kneading temperature is 170˜230° C.
 21. The method for forming the composite fiber as claimed in claim 16, wherein the kneading is performed by using a twin-screw kneading machine.
 22. The method for forming the composite fiber as claimed in claim 21, wherein a rotating speed of the screw is 200˜300 rpm. 